Injection device



June 17', 1969 MLLGE-RQDT 3,450,134

INJECTION DEVICE Filed July 5, 1966 INVENTOR WERNER WILLGERODT United States Patent US. Cl. 128-214 6 Claims ABSTRACT OF THE DISCLOSURE An injection syringe for medical devices. The syringe includes a piston and a cylinder in which the piston head reciprocates. A circumferential groove surrounds the piston, and a supply tube extends axially with respect to the piston and has a discharge end communicating with the circumferential groove. A withdrawing tube also extends axially with respect to the piston, and this latter tube has its intake end communicating with the groove. A means for supplying a liquid sealing medium to the supply tube communicates with the latter during the movement of the piston within the cylinder and a means for withdrawing the liquid sealing medium from the withdrawal tube communicates with the latter tube also during movement of the piston within the cylinder. In this way, it is possible to maintain a liquid sealing medium within the groove to provide a sealed slidable engagement between the piston and the cylinder.

The invention relates generally to an injection syringe for medical devices, for instance, blood exchange devices, and particularly to a gas-tight sealing of the cylinder chambers thereof.

Injection syringes are known in which the piston moving in a glass cylinder has a sealing ring which seals ofi. each cylinder chamber against the other. The brake ring may be made of metal, plastic or any other suitable material.

The shortcoming of these pistons is that the two cylinder chambers which are separated by the piston are not sealed gas tight with respect to each other, so that an air embolism may take place during blood transfusion or during blood exchange. Moreover, the circumference of the piston and the inner face of said cylinder are subject to wear during a continuous use of the device, which reduces the durability of the syringe considerably.

A further shortcoming of known blood syringes is, that the wall of the cylinder is internally smeared with blood, after a short operating time.

It is, therefore, an object of the invention to provide a syringe in which the occurrence of an air embolism in the blood during the blood transfusion, or during a blood exchange, is made impossible; to provide a syringe which has long durability.

Another object of the invention is to provide an injection syringe wherein the cylinder chambers are separated from each other in a gas-tight manner, in which no substantial wear occurs between the circumference of the piston and the inner faces of the cylinder during continuous operation and which prevent smearing of the interior of the cylinder walls with blood; and to provide a syringe which has long durability.

In accordance with the invention, these objects are achieved in that a seal is provided by a circumferential groove around the piston, which is filled with a liquid, preferably, a blood plasma or a blood plasma substitute. In a preferred embodiment of the invention, two diametrically spaced bores extend in axial direction within the piston from the outer end face thereof to the circumferential groove therein. The circumferential groove provides a passageway between the two bores. 'Ihese bores extend into a collecting conduit. One of these bores extends into the groove by means of a tube and both bores are provided with hose connections on the front face of the piston to which a hose is connected, which in turn is connected to a liquid supply container or to a waste container, respectively. The bores and hoses may be connected with each other in such a way, as to form a continuous flow from the liquid supply container, to the waste container. When a plurality of coacting syringes to the Waste container are employed, they are connected in series with respect to each other in such a way as to permit a continuous flow of liquid.

For a better understanding of the invention, its operating advantages and the specific objects attained by its use, reference should be had to the following descriptive matter and the accompanying drawing in which:

A single semi-diagrammatic figure shows an embodiment of the invention.

With reference to the figure, it can be seen, that two piston-cylinder arrangements 1 and 2 are shown having their liquid seals connected in series. Only one arrangement 1 shall be described. The piston-cylinder arrangement 1 is provided for an injection syringe 3. In this arrangement, the piston 4 has two diametrically spaced bores 5 and 6 extending in axial direction within the piston from the outer end face 7 thereof to a circumferential groove 8 therein. Clearly the bores 5 and 6 and the circumferential groove might be formed in the cylinder wall. The circumferential groove contains a liquid medium which acts as a seal between piston and cylinder wall. The circumferential groove also provides a passageway between the two bores in the pistons.

A supply tube 10 is carried within the bore 5, and an extended withdrawal tube 11 is carried within the bore 6 in order to assure better mounting of hose connections 12 at the outer end face 7 of the piston.

The extended tube 11 projects into the circumferential groove 8, While the supply tube 10 extends only to the base of circumferential groove 8. The purpose of this arrangement is to keep a defined quantity of liquid medium in the circumferential groove 8. If the extended tube 11 were not provided, the liquid medium which is supplied through the supply tube 10 would immediately flow out of circumferential groove 8. However, in the aforementioned arrangement, the liquid medium can only flow out of the groove 8, when reaching the level of the extended withdrawal tube 11.

A flexible conduit 13 extends from a supply tank 14 containing liquid 15 for the seal between the piston 4 and its cylinder, to hose connection 12 attached to the supply tube 10 at the outer end face 7 of the piston 4. The

liquid level in groove 8 is limited by the extent of projection of the extended withdrawal tube 11 into the groove.

A second flexible conduit 16 is coupled at one end by a second hose connection 12 to the lower end of the extended withdrawal tube 11 at the outer end surface 7 of the piston 4. Thus, when the liquid 15 rises above the extreme projection of the extended withdrawal tube -11 within the circumferential groove 8, the excess liquid will be removed through the tube and the conduit.

The other end of the second flexible conduit 16 is coupled by a hose connection 12 to the end of a supply tube in the second piston-cylinder arrangement 2 exactly similar to the arrangement already described. Thus, sealing liquid is supplied to the circumferential groove 8 of the piston 4 in the second arrangement from the circumferential groove in the first arrangement. When the liquid in this second circumferential groove rises above the projection of the second extended withdrawal tube 11, the excess is removed as described above through a third flexible conduit 17 connected at one end thereof to the end of the tube 11 at the outer end face 7 of the piston 4 by a hose connection 12. The other end of the third flexible conduit is connected to a waste container 18.

A sealing liquid pump 19 is provided for supplying the liquid to the supply container 14 at a desired pressure and rate. Accordingly, sealing liquid, as blood plasma or a blood plasma substitute, may be supplied to one or a sequence of piston cylinder arrangements at a rate to make up for leakage, or in a continuous stream, or at any intermediate rate, to keep the sealing liquid fresh.

Regarding each injection syringe 3, it functions as a single action pump, having a vacuum-pressure chamber operated by a piston-cylinder arrangement 1 or 2, as described above. A single pipe 21, suitably connected, serves to fill the chamber 20 with blood plasma or the like upon the suction stroke of the piston 4 and to deliver thi: liquid as required, through suitable valving (not shown) upon the pressure stroke of the piston.

It is to be noted that, should the sealing liquid leak into the vacuum-pressure chamber 20 it will do no harm because of its selection, and the fact that it is kept perfectly fresh. On the other hand, if blood plasma should leak into the circumferential groove '8 it will not cause smearing of the interior of the cylinder walls because of its dilution by the sealing liquid. Furthermore, the rate of withdrawing and replenishing the sealing liquid in the circumferential groove should be such as to prevent any appreciable accumulation of blood plasma there.

In the particular example shown in the drawing, the injection syringes are not used separately and individually from each other. Instead, they form components of a blood-exchanging device as may be required, for example, in the case of new-born infants where it is necessary to provide the infant with an entirely new supply of blood.

Of course, with such a device, the supply container 14, the waste container 18, and the cylinders 3 are all stationary components. The only moving components, of those illustrated in the drawings, are the pistons 4 which respectively reciprocate in the cylinders 3, and of course, the conduits 13, 16 and 17 move with the pistons 4 at the ends of these conduits which are attached to the lower ends of the tubes 10 and 6. Of course, the flexible conduits 13, 16 and 17 are sufficiently long to be capable of moving with substantially no resistance together with the pistons 4.

The supply container 14 is situated at a predetermined elevation and contains the liquid sealing medium which may be, for example, blood plasma. This container 14 is filled with this latter liquid sealing medium. Inasmuch as this sealing medium has a predetermined viscosity and thus will not, of its own accord, flow through the system, the supply container is provided with a pump 19 which is built onto and has its pressure outlet end communicating with the interior of the supply container 14. By means of this pump 19, the sealing medium is pumped through the flexible conduit 13 up to the fitting 12 of the first piston 4 and then through the tube 10 into the annular groove 8 from where the liquid is pumped through the withdrawal tube 7 into the flexible conduit 16. From the latter, the sealing liquid flows in the identical manner through the piston of the second injection syringe to reach the flexible conduit 17 which delivers the liquid to the waste container 18.

The liquid sealing medium is pumped through the system until a part of the sealing medium reaches the waste container 18. At this moment, there is a perfect seal between each piston 4 and the cylinder in which it slides. If it should happen that during the operation, the sealing medium becomes impure, as, for example, if it should happen that blood which clings to the inner surface of the cylinder gives to the sealing liquid a reddish color, then the pump 19 can again be started so as to pump additional sealing medium through the system from the supply container 14 until the reddish color in the sealing medium has been eliminated. Under no circumstances is there a possibility that the liquid medium will flow of itself out of the system or out of the circumferential groove 8. The reason for this is not only the viscosity of the particular sealing medium which is used but also the fact that the liquid sealing medium is maintained under pressure as a result of the action of the pump 19.

It is to be noted that the sealing medium is not necessarily continuously circulated through the system. Instead, once the medium reaches the waste container, the action of the pump is terminated. Subsequent pumping is only required as in the above example where the sealing medium takes a reddish color indicating that impurities, such as blood clinging to the surface of the cylinder, have been received in the sealing liquid. In such a case subsequent pumping can be carried on until the impurities have been eliminated from the system.

While the above description discloses a preferred embodiment of my invention, my invention is by no means to be limited to the embodiments shown, but rather any limitation shall be so specified in the following claims.

What I claim is:

1. An injection syringe for medical devices comprising a piston, a cylinder in which said piston is reciprocable, a circumferential groove around said piston, a supply tube extending axially with respect to said piston and having a discharge end communicating with said circumferential groove, a withdrawal tube extending axially with respect to said piston and having an intake end communicating with said groove, means connected to said supply tube and extending outwardly of said cylinder for supplying a liquid sealing medium to said groove through said supply tube and communicating with the latter during movement of said piston in said cylinder and means connected to said withdrawl tube and extending outwardly of said cylinder for withdrawing the liquid sealing medium from said groove through said withdrawal tube and communicating with the latter tube also during movement of said piston within said cylinder, whereby a liquid sealing medium within said groove seals the piston and cylinder.

2. An injection syringe as claimed in claim 1, wherein said withdrawal tube is an extended tube having its intake end projecting within said groove, whereby liquid sealing medium covering said intake end is withdrawn from the groove leaving the remaining liquid in the groove.

3. An injection syringe as claimed in claim 1, wherein the circumferential groove is formed in said piston, said tubes extend within said piston, the means for supplying the liquid sealing medium to said supply tube is a supply container and a flexible conduit connected thereto and to an end of said supply tube at the outer face of said piston, and the means for withdrawing the liquid sealing medium from said withdrawal tube is a flexible conduit connected to the end of said withdrawal tube at the end thereof at the outer face of said piston and communicating with a waste container at a lower level than said piston.

4. The injection syringe as claimed in claim 3, wherein said groove, said supply means and said waste container are connected with each other by said conduits 5 6 which are unobstructed in such a manner as to permit an FOREIGN PATENTS uninterrupted flow of said liquid medium.

5. The injection syringe as claimed in claim 3, where- 238,609 5/1962 Australia. in a plurality of syringes are arranged in series with re- 931,484 7 /1963 Great Britain spect to each other. 5

6. The injection syringe as claimed in claim 5 wherein I I said plurality of syringes are connected .with each other RICHARD GAUDET Prlmary Exammer' by said conduits which are unobstructed to permit a continuous flow of said liquid medium.

References .Cited 10 U 5 L UNITED STATES PATENTS 12 273 2,211,456 8/1940 Caldwell 92-174 MARTIN F MAJESTIC, Assistant Examiner. 

